/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.table.planner.plan.trait;

/**
 * Lists all kinds of behaviors to describe whether the node can produce duplicated changes for
 * downstream operators to consume.
 *
 * <p>The trait in each operator is determined by its downstream operators, meaning that downstream
 * defines whether the operator is allowed to output duplicate changes.
 */
public enum DuplicateChanges {

    /** Allow to produce duplicated data for downstream operators to consume. */
    ALLOW,

    /** Disallow to produce duplicated data for downstream operators to consume. */
    DISALLOW,

    /**
     * The {@link DuplicateChanges} is not inferred yet or there are no operators downstream of the
     * operator like sink.
     */
    NONE
}
